<template>
  <div class="pagination">
    <button  @click="$emit('change-pageNo',pageNo-1)"
    :disabled="pageNo==1"
    
    >上一页</button>
    <button  v-show="startAndEnd.start>1" @click="$emit('change-pageNo',1)">1</button>
    <span v-show="startAndEnd.start>2">...</span>
    <button v-for="(_,index) in (startAndEnd.end-startAndEnd.start+1)"
    :key="_"
    
    :class="{active:index+startAndEnd.start==pageNo}"
    
    @click="$emit('change-pageNo',startAndEnd.start+index)"
    
    > {{ startAndEnd.start+index}}</button>
    
    <button v-show="startAndEnd.end>totalPage-1">···</button>
    <button    v-show="startAndEnd.end<totalPage">总页数:{{totalPage}}</button>
    <button @click="$emit('change-pageNo',pageNo+1)"
    :disabled="pageNo===totalPage"
    
    >下一页</button>

    <span>共 {{total}}条</span>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props:["total","pageSize","continues","pageNo",],
  computed:{
//计算总数
totalPage(){
  const {total,pageSize}=this;
  return Math.ceil(total/pageSize)

},
//计算其实也
startAndEnd(){
  const {pageNo,continues,totalPage,}=this
let start,end

if(totalPage<continues){
start=1,
end=totalPage
}else{
  start=pageNo-(continues-1)/2
end=pageNo+(continues-1)/2
if(start<1){
  start=1//起始页最小也得是1
  end=continues
}
if(end>totalPage){
  end=totalPage,//结束页必须是总页码
  start=totalPage-continues+1;
}
}

return {start,end}
}
  },
  
    
};
</script>

<style lang="less" scoped>
.pagination {
  text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #C81623;
      color: #fff;
    }
  }
  span{
    display: inline-block;
    line-height: 28px;
    font-size: 14px;
    color:gray;
    vertical-align: middle;
  }
}
</style>